[An ultrastructural study of the transformation of elementary bodies of Rickettsiella into initial bodies (author's transl)].

An intermediate stage between the elementary and the initial bodies of the Rickettsietta genus is defined as the beginning of an intracellular cycle. It is characterized by several structural changes in the dense elementary body: the cytoplasm becomes less electron-dense; thus, the nucleoid and the ribosomes are visible. The inner layer of the cell-wall becomes progressively clearer and the trilamellar structure of the inner and outer membranes appears distinctly. 'preinitial body' is proposed as name of this stage of development.